THE IMS IP MULTIMEDIA CONCEPTS AND SERVICES PDF

Friday, June 7, 2019

IMS. IP Multimedia Concepts and Services in the Mobile Domain is a logical entity of the P-CSCF, and in Release 6 the PDF is a stand-alone function. Based on the received information the PDF is able to derive authorized IP QoS information that will be passed to the GGSN when IP Multimedia Subsystem. With 35% new material, The IMS,IP Multimedia Concepts and Services, 3rd Edition has been completely revised to include updated chapters as well as totally.

Introductory concepts and IMS general terminology IP Multimedia Subsystem ( IMS) is a Service Delivery Architecture . ❖May contain a PDF which. John Wiley and Sons Ltd, United Kingdom, Hardback. Condition: New. 2nd Revised edition. Language: English. Brand New Book. The IMS: IP. architecture based on new concepts, new technologies, new partners and IMS can enable IP interoperability for real-time services between fixed and mobile.

On the contrary, the visited service control imposes some limitations. It requires a multiple relationship and roaming models between operators.

Service development is slower as both the visited and home network would need to support similar services, otherwise roaming users would experience service degradations. In addition, the number of interoperator reference points increase, which requires complicated solutions e.

THE IMS: IP Multimedia Concepts and Services, 3rd Edition

Further services are run on top of the IMS signalling network. In some cases it may be impossible to distinguish between functionality at the upper and lower layers. The layered approach aims at a minimum dependence between layers.

The layered approach increases the importance of the application layer as services are designed to work independent of the access network and the IMS is equipped to bridge the gap between them.

Whether the subscriber is using a mobile phone or a PC client to communicate, the same presence and group list functions in IMS will be used. These include:. This will enable service providers to use the characteristics and capabilities of the currently selected device and its network access method and adapt to it dynamically. IP Multimedia Subsystem architecture 19 2. In Release 6 e. In this book we use GPRS as an example.

Session management and routing family CSCFs. For instance, how does CSCF obtain user data from databases? Additionally, GPRS functions are described at the end of this section. Each CSCF has its own special tasks and these tasks are described in the following subsections. Both entities are able to release sessions on behalf of the user e. As the SIP protocol is a text-based signalling protocol, it contains a large number of headers and header parameters, including extensions and security-related information which means that their message sizes are larger than with binary-encoded protocols.

SIP compression is described in Sections 3. See Sections This concept is covered in Section 3. How this is done is shown in Section 3. This functionality will not vanish when IMS emergency sessions are supported, as in certain roaming cases it is possible that the UE does not itself recognize that the user has dialled an emergency number.

The assignment of the S-CSCF will take place when a user is registering with the network or a user receives a SIP request while she is unregistered from the network but has services related to an unregistered state e.

This procedure is described in more detail in Section 3.

Routing incoming requests further to an assigned S-CSCF or the application server in case of public service identity see Section THIG is further explained in Section 2. Based on the authentication data it generates a challenge to the UE.

After receiving the response and verifying it the S-CSCF accepts the registration and starts supervising the registration status. User identities consist of two types: private and public user identities see Sections 3. The private user identity is a user identity that is assigned by the home network operator and is used for such purposes as registration and authorization, while the public user identity is the identity that other users can use for requesting communication with the end-user.

IMS access parameters are used to set up sessions and include parameters like user authentication, roaming authorization and allocated S-CSCF names. Service-triggering information enables SIP service execution.

The structure of the HSS is shown in Figure 2. This enables subscriber access to PS domain services. The AUC stores a secret key for each mobile subscriber, which is used to generate dynamic security data for each mobile subscriber. Security data are also used to provide integrity protection and ciphering of the communication over the radio path between the UE and the network. There may be more than one HSS in a home network, depending on the number of mobile subscribers, the capacity of the Figure 2.

The IMS: IP Multimedia Concepts and Services

The IMS 24 equipment and the organization of the network. There are multiple reference points between the HSS and other network entities. The third party here means a network or a standalone AS. The main functions of the AS are:. The capability to originate SIP requests.

The capability to send accounting information to the charging functions.

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Using the OSA an operator may utilize such service capability features as call control, user interaction, user status, data session control, terminal capabilities, account management, charging and policy management for developing services [3GPP TS As the support of OSA services is down to operator choice, it is not architecturally sound to support OSA protocols and features in multiple entities.

An AS may be dedicated to a single service and a user may have more than one service, therefore there may be one or more ASs per subscriber.

Additionally, there may be one or more ASs involved in a single session. The MRFP performs the following functions:. Users can integrate voice, video and text, content sharing and presence as part of their communication and can add or drop services as and when they choose. For example, two people can start a session as a voice session and later on add a game or video component to the same session.

Peer-to-peer applications require end-toend reachability and this connectivity is easiest attainable with IP version 6 IPv6 because IPv6 does not have address shortage.

Description

This is further described in Section 3. IP connectivity can be obtained either from the home network or the visited network.

Obviously, when a user is located in the home network all necessary elements are in the home network and IP connectivity is obtained in that network. This would allow users to use new, fancy IMS services even when they are roaming in an area that does not have an IMS network but provides IP connectivity. IP Multimedia Subsystem architecture 13 customers to the home network. This will no longer be the case with the IMS.

The UE is able to negotiate such parameters as:. Media type bit rate, packet size, packet transport frequency. Usage of RTP payload for media types. Bandwidth adaptation. After negotiating the parameters at the application level, UEs reserve suitable resources from the access network. When end-to-end QoS is created, the UEs encode and packetize individual media types with an appropriate protocol e. It is assumed that operators negotiate service-level agreements for guaranteeing the required QoS in the interconnection backbone.

This allows an operator to verify that its bearer resources are not misused e.

The IMS This allows IMS to release an ongoing session because, for instance, the user is no longer in the coverage area. Therefore, the IMS provides at least a similar level of security as the corresponding GPRS and circuit-switched networks: for example, the IMS ensures that users are authenticated before they can start using services, and users are able to request privacy when engaged in a session.

Section 3. An overview of applied security solutions is depicted in Figure 2. Figure 2. This includes, say, the capability to charge just the calling party or to charge both the calling party and the called party based on used resources in the transport level.

However, an operator might be interested to correlate charging information generated at transport and IMS service and content charging levels.

This capability is provided if an operator utilizes a policy control reference point. The charging correlation mechanism is further described in Section 3. As IMS sessions may include multiple media components e.

Prepaid services are applications that need online charging capabilities. This is the traditional model in which the charging information is collected over a particular period and, at the end of the period, the operator posts a bill to the customer. The roaming feature makes it possible to use services even though the user is not geographically located in the service area of the home The IMS 16 Figure 2.

In addition to these two there exists an IMS circuitswitched roaming case. When a user is not registered or reachable in one domain a session can be routed to the other domain. Some services are similar and available in both domains e. Moreover, people may not be able to switch terminals or subscriptions very rapidly.

This will raise the issue of being able to reach people regardless of what kind of terminals they have or IP Multimedia Subsystem architecture 17 where they live. To be a new, successful communication network technology and architecture the IMS has to be able to connect to as many users as possible.

THE IMS: IP Multimedia Concepts and Services, 3rd Edition

This entity in the second generation 2G is called a visited mobile service switching centre. In the early days of Release 5 both visited and home service control models were supported. The visited service control was dropped because it was a complex solution and did not provide any noticeable added value compared with the home service control.

On the contrary, the visited service control imposes some limitations. It requires a multiple relationship and roaming models between operators. Service development is slower as both the visited and home network would need to support similar services, otherwise roaming users would experience service degradations. In addition, the number of interoperator reference points increase, which requires complicated solutions e. Further services are run on top of the IMS signalling network.

In some cases it may be impossible to distinguish between functionality at the upper and lower layers. The layered approach aims at a minimum dependence between layers. The layered approach increases the importance of the application layer as services are designed to work independent of the access network and the IMS is equipped to bridge the gap between them.

Whether the subscriber is using a mobile phone or a PC client to communicate, the same presence and group list functions in IMS will be used.OMA has recognized that it is not beneficial for each service enabler to have its own mechanism for security, quality of service, charging, session management, etc.

Another advantage with such an architecture is that the user can create, modify and delete such a list and synchronization will automatically take place since the means for uploading and modifying such a buddy list would also have a built-in functionality to notify other devices of changes to the buddy list.

The components that make up a Spec T are: However, it is very likely that the protocol would be SIP. Quality of service: User Data—contains the updated user profile the user profile is explained in Section 3.

This information is delivered by the PDF to the access network in order to enable charging correlation as described in Section 3. She can also use the same list to create a conference call where her buddy list represents the list of participants.